London (AP) - More police officers were being deployed at transport hubs in London amid continuing fears of a terrorist attack, British media reported Thursday.
Sky News reported that transport police were told to cancel days off Friday, and that there would be a heavy police presence across the capital -- including near Luton and Heathrow airports.
The report quoted unnamed sources as saying that members of the emergency services had recently been briefed about how to respond to a Mumbai-style attack on London.
Scotland Yard declined comment on the report, saying they never discuss the specifics of terrorism-related operations. The Home Office said the country faced a real and serious threat from terrorism, but declined to go into details.
The government said the threat level from international terrorism remains at "severe" -- the second-highest level, meaning an attack is highly likely. The level has not changed since Jan. 2010.
"We will police accordingly and use a range of covert and overt tactics which remain under constant review," police said a statement.
BAA, which runs Heathrow and five other terminals, said security at its airports remained at a high level and that the company is vigilant at all times.
The Daily Telegraph reported on its website that train stations across London were put on high alert. Quoting an unnamed security source, it said there was no imminent threat but activity from extremist cells had led to an adjustment in policing levels.
In October, the U.S. State Department advised American citizens living or traveling in Europe to take more precautions following reports that terrorists may be plotting attacks on a European city, possibly a shooting spree similar to the deadly 2008 Mumbai attacks in India.
Britain had not seen a terror attack since that warning, but a Dec. 11 attack in Stockholm, Sweden was linked to the U.K.
Taimour Abdulwahab, who blew himself up on a busy street in Stockholm, injuring two people, had lived and studied in Luton, about 34 miles northwest of London, for years before he was killed in the attack.